An ignition plug is a device that electrically generates a spark in a spark ignition internal combustion engine and ignites a mixed gas. When a high voltage is applied between a center electrode of the ignition plug and a ground electrode, a discharge phenomenon in which insulation between electrodes is broken, a current flows and an electric spark is generated occurs. A voltage level necessary for forming the spark between the electrodes of the ignition plug (hereinafter referred to as ignition request voltage) tends to increase as an air-fuel ratio becomes lean. Therefore, during execution of fuel cut, the ignition request voltage becomes high.
Patent Document 1 discloses that during the fuel cut, the ignition request voltage becomes high and leakage tends to occur in an ignition circuit thereby. Further, for this problem, a controller that corrects an ignition timing to an advance angle side under the fuel cut condition and maintains the ignition request voltage at a low level thereby is disclosed. It is further disclosed that this correction of the ignition timing to the advance angle side is executed when the fuel cut condition continued a plurality of times.
The present inventors recognize documents described below including the document described above as ones associated with the present invention.